The present invention relates in general to automatic signaling and train control systems for railroads and the like and especially high speed rail routes and, more particularly, to systems for automatically indicating the identity, track number, positioned direction and speed of a given train which is transmitted to other trains within a prescribed locality and to a central station all of which is utilized to calculate conditions of impending danger.
Railway signaling devices and, more specifically, those utilized to warn one train of the proximity of another train have been around for many many years. The most fundamental of such devices is the railway flare which is dropped from the rear of a train and burns for a prescribed time indicating the proximity of one train to another by the simple fact that the flare is still burning upon the approach of another train.
As the evolution of the railway industry proceeded, it naturally became important that the proximity of one train to another and thus the possibility of a collision be determined with greater precision. One system which came into use was the so-called block system. In this system, blocks of track were separated by rail insulation. As the train proceeded from one block to another, electrical signals were carried along ground lines to indicate when a train moved from one block to another and thus generate data useful in determining potential collision situations. As trains began operating at higher speeds and in greater frequencies along single or multiple tracks, the block system became inadequate due to the rather extensive expanse from one block to another and thus the timing inaccuracies.
The pressure on the railway industry for ever more efficient systems started the advent of systems which would more accurately determine a given train identity, position, direction and provide appropriate alarms and/or stop signals upon the proximity of two or more trains reaching a critical situation.
These systems employed a number of different transmission systems for the signals generated. One type of transmission would be along the actual rails themselves and/or along antenna wires carried along the railway tracks. In another system, the transmitted signals would be by radio wave transmission to transmitters/receivers associated with the various trains and/or central stations along which the various data would be transmitted, analyzed and the various signal situations generated.
In systems of the foregoing nature, one of the most important and critical pieces of data, i.e. train position, would be created by means of such devices as magnetic transducers positioned selectively along the railway. In these systems, a train positioned at a reference point, i.e. a given terminal position, would be initialized and thereafter that train position reading altered by passing over the magnetic transducers. Such systems would provide train identity, train direction and train position.
One of the disadvantages of the initial reference system is the inherent chance of error. Of course, the system must be initialized to the reference point at the beginning or all data will likewise be in error as will the data if the on train system malfunctions. Additionally, the transducers, upon passage of the train, are subject to variation and failure to register an appropriate count and thus then the entire system is out of calibration creating a further potential danger. Thus, these rather complex initial reference systems, due to their complexity, have inherent accuracy problems and, likewise, are rather expensive both in production and maintenance.
What is desired is an inexpensive and effective system for indicating train railway data such as train position, train direction and track identification which is independent of on train carried equipment and inalterable in its character and operation.